The cultivated lettuce in Shaanxi Province is very large and the yield is also high, which is mainly divided into two seasons: spring cultivation and autumn cultivation. Lettuce prefers a cold and cool climate, summer and autumn temperatures are higher, easy to unripe lettuce, resulting in lettuce slender, poor quality, not suitable for the growth of lettuce, in the four mild areas, you can grow lettuce all year round. The specific method of planting lettuce is as follows:
1. Transplanting time: The temperature of lettuce transplanting should be controlled at 15-20 ° C, the temperature is low, the growth is slow, the temperature is too high, and the growth of seedlings is difficult. In Shangluo City, Shaanxi Province, lettuce seedlings are generally transplanted in early to mid-March in spring and mid-to-late September in autumn. The size of the seedlings is based on the number of leaves, and seedlings with 4-6 leaves are generally transplanted. The nursery time in spring generally takes 30-35 days, and in autumn it only takes about 25 days. The specific time of seedlings can be pushed forward.
2. Transplanting method: 2000-3000 kg of decomposed farm manure per mu when preparing the land, 30 kg of ternary compound fertilizer, 1 kg of borax, 1 kg of zinc sulfate, and then 2 rows of lettuce are planted on the surface, and the planting density in spring is 40 cm and the plant spacing is 30 cm. Autumn is generally 30 cm row spacing. The plant spacing is 25 cm, and the density is appropriately increased when planted later. Water before transplanting to prevent root damage.
After planting lettuce seedlings in the hole, the depth of the soil cover is as deep as the nutrient bowl. After colonization, water, then cover with 0.008 mm thick mulch film, expose the seedlings to the mulch film, and seal the opening with fine soil. Lettuce covered with mulch can increase production and improve quality, and it can be listed more than 15 days in advance, with significant economic benefits.
3. Water and fertilizer management. After transplanting in the spring, water the second water about 15 days, and in the autumn, watering is required 2-3 days after transplanting to avoid seedling wilting. After the slow seedlings, diluted human feces or ammonium bicarbonate can be applied, and then watered for a third time in about 10 days, and then squatting seedlings. Lettuce stems begin to fertilize when they begin to be fertilized, apply 25 kg of ternary compound fertilizer per mu of land, and begin to keep the field moist, every 5-7 days of topdressing, if nitrogen deficiency, you can increase the amount of nitrogen fertilizer application.
4. Pest and disease prevention. Lettuce is prone to downy mildew, cataplexy, sclerotia, spot blight, underground pests, aphids and whitefly and other diseases and insect pests, which need to be observed from the beginning of transplanting, adjust the humidity and precise fertilization of the field, and be prepared for chemical prevention. Underground pests can be treated in the soil before transplanting, and the damage of underground pests is found after transplanting, which can be remedied by irrigating roots.